首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
TheSomogyi-Nelson colorimetric method is applied in a new manner more suitable for evaluating the kinetics of the enzyme hydrolysis of sodium carboxymethylcellulose (Na-CMC) catalyzed by the cellulase complex. By means of selective inhibition of a chosen enzyme from the cellulase complex it became possible to trace the effect of the other enzymes included in its composition.
Kinetik und Mechanismus der Hydrolyse von Natriumcarboxymethylcellulose (Na-CMC) durch einen Cellulase-Komplex
Zusammenfassung Die kolorimetrische Methode nachSomogyi undNelson wird nach einem neuen Verfahren zur Verfolgung der Kinetik der hydrolytischen Spaltung von Natriumcarboxymethylcellulose (Na-CMC), katalysiert durch den Cellulase-Komplex, angewandt. Durch selektive Inhibierung eines bestimmten Enzyms des Cellulase-Komplexes kann man die Wirkung der anderen zu seiner gesamten Zusammensetzung gehörenden Enzyme verfolgen.

Symbols Used E enzyme (E—cellulase;E—exo-cellobiohydrolase;E—-glucosidase) - [E] w weight concentration of enzymeE - S substrate (Na-CMC—sodium carboxymethylcellulose) - [S]0 weight concentration of substrateS - I inhibitor (I—lactose;I—calcium chloride;I—condurrite-B-epoxide) - P product (P—oligosaccharides;P—cellobiose;P—D-glucose) - P end product (K , K , K ) - DP degree of polymerization - DS degree of substitution - ES enzyme-substrate complex (E S, E S, E S) - EP enzyme-product complex (E P, E P) - EI enzyme-inhibitor complex (E I, E I, E I) - M s molecular mass of substrateS - K s substrate constant (K s , K s , K s ) - K I inhibitor constant (K I , K I , K I ) - K m Michaelis-Menten constant - k +1,k +2 (k +2 ,k +2 ,k +2 ) forward rate constants - k –1 reverse rate constant - 0 initial rate of reaction - V maximal reaction rate - A change in absorbance - molar absorption coefficient - wavelength Herrn Prof. Dr.Hans Tuppy zum 60. Geburtstag herzlichst gewidmet.  相似文献   

2.
The1H-NMR-spectral data of 2-chloro-1.3.2-dioxarsolane are presented and discussed. The protons of the methylene groups form in concentrated solutions by rapide chlorine exchange anAAAA spin system. In dilute solutions the protons form anAABB spin system, which is changed to anAAAA system by addition of chlorine ions.The vicinal H–C–C–H-coupling constants indicate a twist-envelope conformation.

Mit 1 Abbildung  相似文献   

3.
1-(3,4-Dimethoxyphenyl)-1-aminomethylcyclopentane (IV) was condensed with substituted phenylacetyl and benzpyl chlorides to synthesize 1-[R,R,R-phenylacet(benz)amidomethyl]-1-(3,4-dimethoxyphenyl)cyclopentanes (VI), which were converted to 1-[R,R,R-phenyl(benzyl)]-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-4-spirocyclopentanes (IX) by cyclization and subsequent reduction. Reduction of VI yielded the corresponding secondary amines (VII). The compounds obtained were subjected to Chromatographic analysis. The IR spectra were investigated. Compounds VII and IX were subjected to pharmacological testing.See [6] for communication IV.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 637–640, May, 1971.  相似文献   

4.
The ruthenium complexes with tetra-15-crown-5-phthalocyanine and various axial ligands were synthesized and characterized by spectroscopy. A method for the synthesis of bisaxially coordinated ruthenium(ii) tetra-15-crown-5-phthalocyaninates with the N-donor ligands (R4Pc)Ru(L2) (R4Pc2– = [4,5,4",5",4,5,4,5-tetrakis(1,4,7,10,13-pentaoxotridecamethylene)phthalocyaninate-ion], L is trimethylamine (Me3N), pyridine (py), isoquinoline (iqnl), triethylamine (Et3N), pyrazine (pyz)) was developed. The preparation technique involves selective decarbonylation of (R4Pc)Ru(CO)(MeOH) on treatment with Me3NO in excess N-donor solvent.  相似文献   

5.
Summary From a methanolic extract of the roots ofPrangos ferulacea (L) Lindl., growing in the Nakhichevan ASSR, in addition to the compounds found previously, another six substances (I–VI) have been isolated, of which (I) and (VI) have been identified as, respectively, meransin hydrate monoacetate, found for the first time in nature, and umbelliferone: and in the study of a crystalline mixture obtained from the resin of the roots of the plant under investigation collected in Armenia, two coumarins — (VII) and (VIII) — have been isolated.On the basis of a study of IR, NMR, and mass spectra and chemical properties, the structures of the six new cumarin derivatives (II–V, VII, and VIII) have been established. Compound (II) has the structure of 8-(3-methylbutenyloxy)furo-2,3:7,6-coumarin and has been called feruliden; (III) is 7-hydroxy-8-(3-hydroxy-2-senecioyloxyisopentyl) coumarin and has been called ferudiol; (IV) is 7-hydroxy-8-(3-methoxy-2-senecioyloxyisopentyl) coumarin; (V) is 5-[1-(2,3-dihydroxy-3-methylbutyroyloxy)-1-methylethyl]-4,5-dihydrofuro-2,3:7,6-coumarin and has been called lindiol; (VII) is 8-(2-hydroxy-3-methylbut-3-enyloxy)-7-methoxycoumarin and has been called ferudenol; (VIII) is 7-methoxy-8-(3-methyl-2-oxobut-3-enyl)coumarin and has been called prangone.Leningrad Sanitary-Hygenic Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 568–574, September–October, 1974.  相似文献   

6.
Using the Fokker-Planck version of an approximate Boltzmann equation for the ion (translational) energy distribution function fI we have calculated the deviation, k, of the non-equilibrium ion-(polar)molecule reaction rate coefficient k (based) on fI from its equilibrium value k(0). The D (dipole moment)-dependence of the reaction cross section applied leads to a corresponding dependence of k on D.
- , k - ( fI) k(0). k D.
  相似文献   

7.
The structure of psolusoside B — a minor triterpene oligoglycoside from the holothurianPsolus fabricii and the main glycoside fromPsolus sp. has been determined by the methods of partial acid hydrolysis, methylation,13C NMR, and FAB mass spectrometry as 20S-acetoxy-3-{2-O-[O--D-glucopyranosyl-(1 4)-O--D-glucopyranosyl]-4-O-(6-O-sulfato--D-glucopyranosyl)--D-xylo-pyranosyloxy}holosta-7,25-diene-18,16-carbolactone. 3-[O-(3-O-Methyl-6-O-sulfato--D-glucopyranosyl)-(1 3)-O-(6-O-sulfato--D-glucopyranosyl)-(1 4)-O--D-quinovopyranosyl-(12)--D-xylopyranosyloxy]holosta-9(11),25-dien-16-one (psolusoside A), known previously forPsolus fabricii, has been identified in a holothurian —Psolus sp. — from Kraternaya Bay (island of Ushishir).Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 361–368, May–June, 1989.  相似文献   

8.
Adsorption of ethylene on an iridium surface proceeds with a high sticking coefficient. The species adsorbed at T=300 K have the structure of ethylidyne (C–CH3). At T500 K the hydrocarbon molecules are decomposed on the surface forming a carbon layer.
. , T=300 K (C–CH3). 500 K, , .
  相似文献   

9.
Summary Ruthenium(III) complexes of types [Ru(L)3], [Ru(L)Cl(H2O)2], [Ru(L)Cl2]n, [Ru(L)Cl(H2O)]n(LH =Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; LH2=Schiff bases derived from anthranilic acid and salicylaldehyde oro-hydroxyacetophenone; LH=Schiff bases derived fromp-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde orm-hydroxyacetophenone; LH2=Schiff bases derived fromp-aminobenzoic acid and salicylaldehyde oro-hydroxyacetophenone) have been synthesized and characterized on the basis of elemental analyses, conductance, magnetic moment and spectral (electronic, i.r. and1H n.m.r.) data. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters have been evaluated. On the basis of the electronic spectra, an octahedral geometry has been established for all these complexes except [Ru(L)Cl2]n. The complexes [Ru(L)Cl2]n are pentacoordinate and a trigonal-bipyramidal environment, D3h, is suggested for the ruthenium(III) ion. The thermal behaviour of these complexes has also been studied by t.g., d.t.g and d.s.c techniques. Heats of reaction for the decomposition steps were calculated from the d.s.c. curves. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid were also investigated.  相似文献   

10.
A method is proposed for the evaluation of quantum yields of photochemical reactions studied in the presence of absorbing additives using cylindrical sample tubes.
.
  相似文献   

11.
Conversion of paraffins on TsVK and Y zeolites follow a similar mechanism yielding the same intermediates. Low selectivity of Y zeolites with respect to aromatic hydrocarbons is attributed to the strong adsorption of these hydrocarbons on zeolites. It is assumed that the centers of strong adsorption are Al3+ ions in cationic positions in zeolite.
, . . , Al3+ .
  相似文献   

12.
It has been shown that the compounds obtained previously corresponding in comparison to the -[4-(5-carboxymethyl-2-hydroxyphenoxy)3-methoxyphenyl]ethylamide of 4-benzyloxyphenylacetic acid have practically the same spectra and on further condensation with 3-bromo-4-hydroxy-5-methoxyphenylethylamine give an equilibrium mixture of diamide compounds. The difference in the physicochemical properties of the diphenyl esters and the diamides can be explained by steric differences. On cyclization, the diamides are converted into bis-dihydroisoquinoline compounds of the same elementary composition. The hydrochloride of 7-[2-acetoxy-5-(7-acetoxy-8-bromo-6methoxy-3, 4dihydroisoquinol-1-ylmethyl)phenoxyl)-1-(4-benzyloxybenzyl)-6-methoxy-3,4-dihydroisoquinoline, with mp 180–181° C, after saponification, intramolecular Ullman condensation, reduction, and stepwise methylation, was converted into isomeric tubocurarin iodides with mp 189–190.5° C, 164–166.5° C, 257–260.5° C, and 210–212° C, which were separated on the basis of their different solubilities in organic solvents and water.For part XII, see [1].  相似文献   

13.
Using the flow ESR method, the rates of the reaction between the radical complex Ti(IV)(O 2 ) and one-electron reductants in aqueous solution have been measured. The redox potential for the Ti(IV) (O 2 )/Ti(IV) (O 2 2– ) couple is about 1.7 V.
Ti(IV)(O 2 ) . - Ti(IV)(O 2 )/Ti(IV)(O 2 2– ) 1,7 .
  相似文献   

14.
Beryllium precipitation from the Cu-rich matrix in a Cu–2 mass% Be–0.2 mass% Mg alloy homogenized and quenched from 1073 K was studied by differential scanning calorimetry (DSC). The DSC traces showed two main exothermic effects, A and B, each comprising two subeffects: A1 and A2 , and B1 and B2 respectively. Effects A1 and A2 correspond to the precipitation of GP zones and subsequent overlapping and independent precipitation of the phase. Only at very low heating rates can be inherited from GP zones. Effects B1 and B2 correspond to heat evolved during transitions to the states with and phases, respectively. Heat effect A can be quantitatively described in terms of solid solubilities before and after precipitation, and of the precipitation heats of the phases involved. The heat content of the combined GP zone/ phase precipitation effect was proportional to the number of beryllium atoms precipitated, yielding an average value of 21 kJ mol–1 beryllium for beryllium precipitation. It was shown that the phase arises from the combined transition from states with GP zones and phases, whereas arises from the transition of states with and phases. The apparent activation energies associated with GP zones and , and phases are 1.16±0.08, 1.18±0.07, 1.37±0.08 and 1.74±0.09 eV, respectively. These values are discussed in terms of the mobility of dissolved atoms related to the concentrations of excess vacancies and solute-vacancy complexes, and the direction of plate-like precipitate growth (either normal or perpendicular to the plate). It is inferred that the main roles of magnesium are to decrease the amount and rate of GP formation, to enhance the volume fraction of and to suppress the discontinuous precipitation of .This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

15.
Thermal analysis of manganese dioxide in controlled atmospheres   总被引:1,自引:0,他引:1  
TG and DTA curves of-MnO2 have been obtained in nitrogen, air and oxygen. The reactions MnO2Mn2O3 and Mn2O3 Mn3O4 were observed in the ranges 450° to 600° and 750° to 1100° respectively, and the decomposition temperatures are affected by the partial pressure of oxygen. The endotherm at 1200° is unaffected by the atmosphere and is not accompanied by weight loss. It is, therefore, due to a polymorphic transformation of Mn3O4 rather than formation of MnO. Reaction to form MnO was observed by TG in nitrogen above 1400°, but did not occur on heating in oxygen to 1500°.
Zusammenfassung Die TG und DTA Kurven von-MnO2 wurden in Stickstoff, Luft und Sauerstoff ermittelt. Die Umwandlungen MnO2 Mn2O3 und Mn2O3 Mn3O4 wurden im Temperaturbereich von 450° bis 600° bzw. 750° bis 1100° beobachtet. Die Zersetzungstemperaturen werden durch den partiellen Sauerstoffdruck beeinflußt. Der endendothermische Vorgang von 1200° bleibt von der Atmosphäre unbeeinflußt, ist mit keinem Gewichtsverlust verbunden. Er ist eher einer polymorphen Umwandlung von Mn3O4 als der Bildung von MnO zuzuschreiben. Die Bildung von MnO wurde thermogravimetrisch in Stickstoff oberhalb 1400° beobachtet, nicht jedoch in Sauerstoff bis zu 1500°.

Résumé Etude de-MnO2 par TG et par ATD, dans l'azote, dans l'air et dans l'oxygène. Entre 450 et 600° on observe la réaction MnO2Mn2O3 et entre 750 et 1100° Mn2O3 Mn3O4. La pression partielle de l'oxygène influence la température de la décomposition. A 1200°, il apparaît un phénomène endothermique undépendant de la nature de l'atmosphère et qui ne s'accompagne d'aucune variation de poids. C'est pourquoi il est attribué à une transformation polymorphique de Mn3O4 plutôt qu'à la formation de MnO. Celle-ci s'observe en TG au-dessus de 1400°, dans l'azote, mais ne se produit pas par chauffage dans l'oxygène jusqu'à 1500°.

, -MnO2. , MnO2 Mn2O3 Mn2O3 Mn3O4 450°–600° 750°–1100°, , . 1200° . , n34, MnO. MnO 1400°, , 1500° .


The authors wish to thank Dr. D. Dollimore and Dr. R. C. Mackenzie for suggesting the problem, and the S.R.C. for a research assistantship to D.M.T.  相似文献   

16.
Zusammenfassung Die manganreiche Seite der Systeme Mn–V und Mn–Cr wurde hochtemperatur-röntgenographisch untersucht. Im System Mn–V treten bei 90 At% Mn zwei bisher nicht beobachtete Phasen, und , mit -bzw. -Manganstruktur auf. Diese gehören möglicherweise der Klasse der -bzw. -Phasen an. Die -Mischphase besitzt einen größeren Existenzbereich als in der Literatur angegeben. Die Existenz der -Phase Mn3V, sowie die Phasenzustände bis 80 At% Mn und bei manganreicheren Legierungen unterhalb 700°C werden bestätigt. Das lineare thermische Ausdehnungsverhalten der Phasen , und sowie des -und -Mischkristalls werden angegeben. Für den manganreichen Teil wird ein vorläufiges Zustandsdiagramm entworfen. Im System Mn–Cr konnte in großen Zügen Über-einstimmung mit Literaturangaben gefunden werden. Es wird das lineare thermische Ausdehnungsverhalten der -Phase Mn3Cr angegeben.
High temperature X-ray investigation of Mn—rich Mn—V and Mn—Cr alloys
The manganese rich portions of the phase diagrams Mn–V and Mn–Cr have been investigated by means of a high temperature X-ray technique. In the system Mn–V two new phases, and , have been observed with -manganese and -manganese type structure, resp. These phases are probably to be classified as -and -phase. The -manganese solid solution with vanadium has a wider range of homogeneity as compared with previous work. The existence of a -phase Mn3V and phase equilibria below 700°C reported previously could be confirmed. The linear thermal expansion of the intermetallic compounds , , , the -and -manganese solid solutions with vanadium has been evaluated. A tentative phase diagram for the manganese rich portion is given. The main features of the system Mn–Cr according to previous investigations could be confirmed. The linear thermal expansion of the -phase Mn3Cr is reported.


Mit 8 Abbildungen

Herrn Prof. Dr.Hans Nowotny in Dankbarkeit gewidmet.  相似文献   

17.
Model reactions of silica-supported zirconium hydrides (Si—O—)3ZrH and (Si—O—)2ZrH2 with methane, resulting in cleavage of a C—H bond in the methane molecule and the formation of (Si—O—)3ZrCH3 and (Si—O—)2Zr(H)CH3 as products were studied using the DFT approach with the PBE density functional. The processes proceed as bimolecular reactions without preliminary formation of agostic complexes. According to calculations, zirconium dihydrides (Si—O—)2ZrH2 are more reactive toward the methane C—H bonds than zirconium monohydrides (Si—O—)3ZrH. The calculated activation energies of the reactions with participation of zirconium dihydrides (Si—O—)2ZrH2 are in better agreement with the known experimental data for the Yermakov—Basset catalytic system.  相似文献   

18.
Differential scanning calorimetry is undoubtedly one of the most powerful techniques for investigating the reactions leading to thermoplastic or thermosetting materials. The conditions for the obtaining of reliable experimental results are summarized. A mechanism for the curing of epoxyamine systems is suggested, which is capable of describing the behaviour of stoichiometric and nonstoichiometric mixtures up to high reaction degrees. The advantage of coupling a DSC instrument with a device for the photochemical activation of polymerizations is demonstrated by some examples.
Zusammenfassung Die Differential-Scanning-Kalorimetrie (DSC) gehört ohne Zweifel zu den leistungsfähigsten Methoden der Untersuchung von Bildungsreaktionen thermoplastischer und thermisch härtbarer Substanzen. Die Bedingungen zur Gewinnung zuverlässiger experimenteller Ergebnisse werden zusammengestellt. Für die Härtung von Epoxid-Amin-Systemen wird ein Mechanismus vorgeschlagen, der das Verhalten stöchiometrischer und nichtstöchiometrischer Mischungen bis zu hohen Umsätzen beschreiben kann. Die Vorzüge der Kopplung eines DSC-Instruments mit einer Einrichtung für die photochemische Aktivierung von Polymerisationen wird an einigen Beispielen demonstriert.

. . - , . .
  相似文献   

19.
Crystallization of iron phosphate glasses   总被引:1,自引:0,他引:1  
Differential thermal analysis (DTA), thermogravimetric analysis (TG), X-ray diffraction and Mössbauer spectroscopy were employed in the investigation of crystalline products of FeOx-P2O5 glasses generated by various heat treatments. In glasses with a high value of =Fe2+/(Fe2+ + Fe3+), absorption of oxygen occurs in a broad temperature range identified by TG. Depending on the value of , two exotherms appear in the DTA curves, the low-temperature one corresponding to crystallization of the Fe3(PO4)2 type regions, and the high-temperature one being related to various phases with dominating FePO4. Each exotherm has its own transformation region, identical in absolute value. The Mössbauer spectra of glasses which underwent thermal treatment at higher temperatures exhibit some indication of phases of the types Fe3(PO4)2 · xH2O and FePO4 · xH2O.
Zusammenfassung Differentialthermoanalyse (DTA), thermogravimetrische Analyse (TG), Röntgendiffraktion und Mössbauerspektroskopie wurden bei der Untersuchung (von kristalliner Produkte) durch verschiedene thermische Behandlungen hergestellten FeOx-P2O5 Gläsern eingesetzt. In den Glasarten mit einem hohen Wert von =Fe2+/(Fe2+ + Fe3+) erfolgt die Sauerstoffabsorption in einem durch TG [nachgewiesenen breiten Temperaturbereich. In Abhängigkeit von dem -Wert erscheinen zwei Exothermen in den DTA-Kurven, von denen der bei niedriger Temperatur die Kristallisation des Fe3(PO4)2 entspricht, und jener bei höheren Temperaturen in verschiedenen Phasen dem FePO4. Jede Exotherme hat ihr eigenes Umwandlungsgebiet, das in absolutem Wert identisch ist. Die Mössbauer-Spektren der Gläser welche einer Wärmebehandlung bei höheren Temperaturen unterzogen worden sind, weisen einige Indikationsphasen der Typen Fe3(PO4)2 · xH2O und FePO4 · xH2O auf.

, , FeOx-P2O5, . , =Fe2+/(Fe2++Fe3+) . , - : Fe3(PO4)2, – FePO4. , . , , Fe3(PO4)2 · 2 FePO4 · 2.


The authors thank Mrs. Simonyiová for assistance in the experimental part of these investigations, and Dr. Horváth and Dr. Vondrovic for performing the X-ray and TG analyses.  相似文献   

20.
The Stoichiometry and the kinetics of thermal decomposition of the title compounds were studied. The results were correlated with the structures of the Cu(II) coordination polyhedra, which have in general a 4+2 type of coordination. It was shown that the equatorial Cu-H2O bond distances are important for the found decomposition stoichiometries. As an intermediate of thermal decomposition, Cu(H2O)5(CH3C6H4SO3)2 was prepared and characterized via its IR and electronic spectra and powder X-ray diffractogram. The experimental activation energies increase with increasing degree of tetragonality of the Cu(II) coordination polyhedron forX =C6H5SO3 and D-C10 H 15OSO3, but decrease forX =4-CH3C6H4SO3. TheE * value found for the decomposition of the latter compound can not be attributed to the chemical reaction.
Zusammenfassung Die Stöchiometrie und Kinetik der thermischen Zersetzung der Titelverbidungen wurde untersucht. Die Ergebnissen wurden auf die Strukturen der Cu(II) Koordinationspolyeder bezogen, die im allgemeinen eine 4+2 Koordination aufweisen. Die Länge der äquatorialen Cu-H2O Bindung erwies sich als bedeutungsvoll für die ermittelte Stöchiometrie der Zersetzung. Das Zwischenprodukt Cu(H2O)5(CH3C6H4SO3)2 der thermischen Zersetzung wurde dargestellt und mittels IR- und Elektronenspektren sowie Röntgenpulveraufnahmen beschrieben. Mit ansteigendem Tetragonalitätscharakter der Cu(II) Koordinationspolyeder wachsen die experimentell ermittelten Aktivierungsenergien fürX =C6H5SO3 und D-C10H15OSO3 an, nehmen aber fürX = 4-CH3C6H4SO3 ab. Der für letztere Verbindung ermittelteE * Wert kann der chemischen Reaktion nicht zugeschrieben werden.

. , 4 + 2. , Cu-H2O . Cu(H2O)5(CH3C6H4SO3)2 , -. X =C6H5SO3 -C10H15OSO3, X = 4-CH3C6H4SO3. .
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号